Easy to Calculate:
To calculate
a)when no of electrons are upto 10.[+1/2,1,-1/2,0] is recurred.
for example:no of electrons is 5 then 1st electron-->+1/2
2nd electron -->1
3rd electron-->-1/2
4th electron--->0
5th electron --->+1/2
Thus bond order for 5 elctron containing molecule is +1/2.
case2: from 11 onwards ,remember that 14 refers to 3(bond order)
Decrease 0.5 from every deviation from 14 for every digit.
for example :no of electrons is 12 then 14 refers to 3
13 refers to 3-0.5=2.5
12 refers to 3-0.5-0.5=2
thus the molecule with no of electrons =12 then Bondorder is 2
for example :no of electrons is 17 then 14 refers to 3
15 refers to 2.5
16 refers to 2
17 refers to 1.5
thus the molecule with no of electrons is 17 has a bond order of 1.5
1)H2 + -->2+1=-1/2bond order(unstable)
H2 -->2elecctrons=1bond order(stable)
H2- --->1 electron =+1/2bond order(unstable)
H22- ---->0 electron =0 bond order -stable
2)He22+ ---->4+2 electrons=1bond order(stable)
He2+ ---> 4+1 electron = 0 bondorder(stable)
He2 ----> 4electron =0 bondorder(stable)
3)Be2 ----> 8electron =0 bondorder(stable)
B
2 ---------> 10 electron = 1 bondorder (atable)
Li2 ---------> 6electrons = 1bondorder(stable)